The cyclodimerisation of 3-methyl-2-butenenitrile

3-Methyl-2-butenenitrile (1) cyclodimerised on treatment with lithium diisopropylamide in dimethoxyethane at temperatures between ?78°C and 0°C to 3-amino-4-cyano-1,5,5-trimethyl-1,3-cyclohexadiene (2) the structure of which was established by acid hydrolysis to the known 4-cyano-1,5,5-trimethyl-1-cyclohexene-3-one (3).     

Solid-supported synthesis of a peptide beta-turn mimetic

[structure: see text]The solid-supported synthesis of a bicyclic diketopiperazine, a potential peptide beta-turn mimetic, is described. The Ugi reaction between the resin ester of alpha-N-Boc-diaminopropionic acid (an amine input), alpha-bromo acid, aldehyde, and isocyanide is the key step in the proposed protocol.     

Conical parametric scattering of a single extraordinary beam in BaTiO3 crystal

In this paper, the parametric scattering of a single extraordinary polarized beam of laser in BaTiO₃ photorefractive crystal has been investigated experimentally and theoretically. The resulting pattern consists of beam fanning, isotropic ring, and anisotropic one. Among all parts of scattering pattern, isotropic ring has not been studied as much as beam fanning and anisotropic ring, and there still are some differences in reports about it. Therefore, the study has mainly focused on this part. In this experimental configuration, isotropic ring is just visible in positive angles although the other parts of parametric scattering pattern can be visible from behind and in front of the crystal. In addition to steady state pattern in forward and backward directions, its transient behavior with the rotation of crystal has been studied. The results of experiments have been analyzed carefully, and their theoretical explanations have been presented based on the standard theory of parametric scattering in photorefractive crystals. It has been shown that this configuration corresponds to the so called parametric B-process scattering.     

A study of hadronic decays of the ϒ′

We present a detailed study of the decays ?′ → π⁺π^?? and ?′ → π⁰π⁰?, where the ? decays subsequently to e⁺e^? or μ⁺μ^?. The results are obtained from a sample of 146 000 ?′ decays observed with the CUSB detector at the Cornell Electron Storage Ring. We derive branching fractions of (18.9 ± 2.6)% for ?′ → π′π^?? and (10.3 ± 2.3)% for ?′ → π⁰π⁰?, and determined partial widths for these decays. Invariant mass and angular distributions of both the π⁺π^? and π⁰π⁰ systems are presented. We also set a limit on the branching fraction for ?′ → η? of less than 0.2% at the 90% confidence level.     

Condensed thiophenes from sulfur bridging. II. Catalyzed reaction of azabiaryls with hydrogen sulfide

Sulfur bridging inlo the phenylpyridines, 2- and 3-phenylquinolines, and the symmetric bi-pyridines was effected by means of hydrogen sulfide and an alumina catalyst at 630° to give [1]benzothienopyridines, [1]benzothienoquinolines, and thienodipyridines, respectively. Structures of products were assigned on the bases of spectral and chromatographic studies, as well as of separate syntheses. Relative yields of the various products are rationalized in terms of a model for interaction between a chemisorbed sulfur atom and the substrate molecule.     

Solving chance-constrained combinatorial problems to optimality

The aim of this paper is to provide new efficient methods for solving general chance-constrained integer linear programs to optimality. Valid linear inequalities are given for these problems. They are proved to characterize properly the set of solutions. They are based on a specific scenario, whose definition impacts strongly on the quality of the linear relaxation built. A branch-and-cut algorithm is described to solve chance-constrained combinatorial problems to optimality. Numerical tests validate the theoretical analysis and illustrate the practical efficiency of the proposed approach.     

Two syntheses of 5-chloro-3-(2-thienyl)-2,1-benzisoxazole

5-Chloro-3-(2-thienyl)-2,1-benzisoxazole ( 2 ) resulted from condensation of (a) o-nitrobenzaldehyde with thiophene in the presence of hydrochloric acid and (b) p-chloronitrobenzene with 2-cyanomethylthiophene. Spectral data for ( 2 ) are presented and interpreted.     

Search for Higgs scalars in upsilon decays

We have searched for the decay of ?'s into a monochromatic photon accompanied by other particles as a signal for the reaction ?→γ+Higgs. Two different methods are presented both with null result. While we are not sensitive to the branching ratios predicted by the standard model with a minimal Higgs content, we can put limits on the possible values of the lowest Higgs mass and the ratio of the vacuum expectation values for more complex models. Our results are also of interest with respect to the ξ(2.2) being a Higgs in the context of such models.